Musannaf Ibn Abi Shaybah

Ibrahim (may Allah have mercy on him) said: If an umm walad commits an immoral act, she will not return to slavery; rather, she will remain in her current state. When her master dies, she will be considered free.

Hazrat Hasan (may Allah be pleased with him) and Ibrahim (may Allah have mercy on him) did not consider the sale of an umm walad to be valid, even if she committed any immoral act, and Hazrat Ibn Sirin was of the opinion that her sale was permissible.

Hazrat Umar bin Abdul Aziz wrote that an Umm Walad, even if she commits an immoral act, is free.

Hazrat Sha'bi (may Allah have mercy on him) says that no new matter (incident) will return an Umm Walad to slavery.

Hazrat Umar bin Abdul Aziz says that even if an Umm Walad commits an immoral act, she should not be sold.

Hazrat Salim bin Abdullah (may Allah be pleased with him) was asked if an umm walad commits an immoral act, can I sell her? He (may Allah have mercy on him) replied: No, her wrongdoing is upon herself (the burden is on her). She is free.

Hazrat Umar (may Allah be pleased with him) said regarding Umm Walad: If she remains chaste and a Muslim, then she is free, and if she commits a wrong act, becomes a disbeliever, and commits adultery, then she will return to slavery.